A raisin could tell you how clever your toddler will be by the age of eight. A wrinkly bit of dried fruit? Yes, really ...

Research has found that the raisin test can predict how smart your child will be at school and how well they will be able to focus on their lessons.

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University of Warwick academics used a raisin and plastic cup to test toddlers. They placed the raisin under the cup and asked toddlers to wait until they were told they could touch and eat the raisin. The toddlers (20 months) were asked to wait for 60 seconds.

They found that the children who obeyed instructions and waited before eating the raisin later did better at school than those who just dived in and gobbled it up.

They also found that children born very prematurely were more likely to take the raisin before the allotted time of one minute.

The toddlers were evaluated again when they were eight, using three different tests that assessed academic achievement and their attention spans.

The toddlers who resisted the temptation to eat the raisin before 60 seconds were found to have an IQ of seven points higher aged eight than those that rushed in and chowed down.

Researchers concluded that the worse the child scored on the raisin test, the more likely they were to have poor attention skills and low academic achievement at eight years old.

They also believe that being able to identify cognitive problems at an early age could result in being able to offer early intervention to help children with their learning and development.

Lead researcher Professor Deieter Wolke said:

"The raisin game is an easy and effective tool that is good at assessing inhibitory control in young children, takes only 5 minutes, and can be used in clinical practice to identify children at risk of attention and learning problems."

The study was published in the Journal of Paediatrics.

The raisin test is similar to the marshmallow test, designed in the 1960s: